Electrolytic process.



M. M. MERRITT.

ELECTRbLYTIC PROCESS.

APPLICATION FlLEDJUNE27|19|/- 1,282,262. Patented Oct. 22, 1918.

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EVIATTIIEVV M. MEREITT, 9F DANVERS, MASSACHUSETTS, ASS IGNOR T0 COPPER TEDD- UCTS COMPANY, 0F IBGSTUN, MASSACHUSETTS, A CORYORATION 0F MAINE.

ELECTROLYTIC PROCESS.

Application filed June 27, 1917.

To all whom it may concern:

Be it known that I, MATTHEW M. MER- RITT, a citizen of the United States, and a resident of Danvers, county of Essex, Commonwealth of Massachusetts, have invented an Improvement in Electrolytic Processes (C), of which the following description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts.

This invention pertains to improvements in electrolytic processes, more particularly, though not exclusively, to improvements in the manufacture of copper or other metallic sheets by electro-deposition on a rotating cathode.

Amon other objects of the invention are to provide a method of depositing such sheets at a relatively rapid rate, of uniform thickness, of smooth and uniform texture and close grain, and of great tensile strength.

In the drawings I have shown a preferred form of apparatus for practising one form of my invention, in which;

Figure 1 is a side elevation, partly in section, showing a rotatin cathode partially immersed in an electro ytic bath.

Fig. 2 is a diagrammatic section through a portion of the cathode.

I have found that by proper correlation of the proportion of the surface of the cathode which is immersed to the speed at which the cathode is rotated, the formation of rough deposits on the deposited sheet caused by liberated hydrogen may be reduced to a' minimum and indeed substantially eliminated, while the so-called burning of the deposits by the use of a high current density may be avoided, while maintaining that rapid rate of deposit which results from the use of such high current density. I have also found that the coarsely crystalline for mation of the sheet with accompanying brittleness, which ordinarily results from the use of high amperage during the deposit, may be avoided by the use of an oily or greasy coating over the surface of the mandrel, which is preferably treated with mercury as described in my copending application, Serial No.

158,428, filed March 29, 1917.

In the drawing I have shown a drum 4, rotatable on the shaft 5 in bearings 6--6 and onlv partially immersed in the electrolytic bath 7.

Specification of Letters Patent.

Patented (lot. 22, 1918,

Serial No. 177.175.

I have found that if the drum or mandrel 4c 1s lmmersed only about one-third of its dlameter I achieve the best results.

By repeated experiment I have found that regardless of the diameter of the drum, the best results are obtained when the drum is rotated at such a rate as to provide approximately 130 feet peripheral speed .per minute. Thus ina large drum a given portion of the surface of the cathode is immersed for a considerably longer time than where a smaller drum is used, but the periods of immerslon are spaced farther apart, the aggregate total period of immersion during any fixed period of time, such as one hour, being the same for either the large or small drum. I have chosen 130 feet peripheral speed per minute because at this speed when a large diameter drum is used the passage of the cathode through the electrolyte is sufiiciently fast to prevent the adherence to the cathode, for any considerable length of time, of any occluded hydrogen, which would tend to form roughnesses on the surface of the deposited sheet, while for similar reasons the sheet will not be burned, even if a relatively high amperage is used to hasten. the electrolytic process. On the other hand, this speed is not suflici'ent to result in carrying over the top of the rotating cathode any considerable amount of the electrolyte which would prevent the liberation of the occluded hydrogen. The peripheral speed of rotation of the drum is preferably such as tocause a considerable film of the electrolyte to be carried out of the bath onthe surface of the rotating mandrel, whichfilm at proper speed practically all runs back. into the bath 7 surface of the sheet.-

Even where a large drum or mandrel is, used, the period of continued immersion of any given portion of the cathode is relatively short, thereby preventing so-called posited metal can pass to afiix themselves directly to the amalgamated surface, the film of rease constantly remains on the outslde surface of the deposited metal and adds greatly to the fineness of the deposited metal. This is probably due to the prevention of the deposit of combinations of ions as is likely to be the case where no film is interposed between the electrolytic bath and the surface of the deposited metal.

Each ion must find its way through the film,

and as the molecular apertures are relatively small, it is impossible for several 1 ons to combine and be deposited on the sheet in substantially the same place at the same time,

as is the case where the surface of the metal deposited on the cathode is in direct contact with the electrolyte. I

The film of grease being constantly on the outside of the deposited sheet tends to prevent adhesion of the occluded hydrogen and to facilitate the washing off of such hydrogen where used with a partially immersed rotating cathode.

I may to some extent reduce the tendency of the ions to combine prior to deposition by introducing into the bath any substance adapted to be dissolved thereby or otherwise to fit in between the molecules of the bath, thereby reducing the paths. through which the deposited ions must travel.

While I have set forth those theories which seem most reasonable to me as exlanations of the improved results attained y my invention, I Wish it understood that the improved results may be explained by other theories, and that my invention should not be limited in any Way by this explanatory matter.

While I have shown in the drawing and have described one specific embodiment of a preferred apparatus with which my inventionmay be practised, it will be understood that changes may be made in such apparatus and in the method of practice of my invention without-departing from the scope thereof. My invention is best defined in the following claims.

Claims:

1. The process of making metallic sheets by electro-deposition, which comprises rotating a cathode at a peripheral speed approximating one hundred and thirty feet per tially coating a rotatable partially sub-' merged cathode with a thin film of grease, and rotating the cathode during the electrodeposition at such speed that a portion of the electrolyte is carried, in a' film, over a portion of the cathode not submerged in the electrolyte, whereby the film of grease is smoothed and whereby the adherence of occluded-hydrogen to the cathode is prevented.

4. Theprocess of making metallic sheets by electrolytic deposit, which comprises coating a mandrel With mercury toprevent the adherence of electrolytically deposited metal to the cathode, applying a thin film of grease to the amalgamated surface of the cathode, said film being of such consistency as to permit the passage of ions therethrough from the electrolyte to the mercury coated surface of the cathode.

Y 5. The method of forming metallic sheets by electrolytic deposit, which comprises initially coating the cathode with a thin film of grease having the capacity .to permit the passage of deposited ions through the film of grease and of maintaining a unitary even film on the exterior of the metal electrolytically deposited.

6; The method of making metallic sheets by electrolytic deposit, which comprisesrotating a partially submerged cathode at a peripheral speed of approximately one hun-- dred and thirty feet per minute, while using a relatively high current density.

7. The,method of making metallic sheets by electrolytic deposit, which comprises providing a cylindrical mandrel immersed approximately one-third in the electrolyte, in initially coating said mandrel with a thin film of grease, and. rotating said mandrel at a peripheral speed approximating one hundred and thirty feet per minute during the period of electro-deposit.

8. The galvanoplastic process, which comprises initially coating a surface of a cathode with a thin film of grease, and electro-depositing metal on the cathode while alter-.

nately immersing such surface in the elec:

trolyte and removing such surface from the electrolyte. In testimony whereof, I have signed my .name to this specification.

MATTHEW M. MERRITT. 

